Gov. Edmund G. (Jerry) Brown Jr. has in effect drawn even with San Diego Mayor Pete Wilson in their race for the U.S. Senate in the Nov. 2 election, according to a poll released Sunday by the Los Angeles Times.

The poll showed 46 percent of the Californians most likely to vote in November supporting Wilson, the Republican nominee, and 42 percent supporting Brown, the Democratic nominee. The remaining 12 percent were undecided or preferred another candidate.

The state-wide poll of 803 likely voters, gleaned from interviews with 1,419 residents, was conducted during a five-day period ended last Thursday. The poll has a margin of error of 5 percent in either direction.

The Times poll is encouraging for Brown, who was trailing Wilson 49 to 35 percent in a Mervin Field California Poll earlier this month.

Brown campaign manager Jack Mayesh said today that he was "extremely encouraged" by the latest poll but added: "Clearly, we have more ground to gain, and we'll step up our efforts in the critical last six weeks."

The Times poll found that Brown's vigorous attacks on Wilson's proposal to redesign Social Security was a major factor in Brown's improved showing. Earlier this summer Wilson proposed that the solvency of the Social Security system could be improved by allowing workers under age 45 to make minimum contributions to the program, thus reducing the benefits they would receive on retirement.

Brown responded by accusing Wilson of wanting to undermine Social Security and he has made it a major campaign issue.

Since the June 8 primary the Brown campaign has spent more than $1 million on advertising, much of it focused on Social Security. About 56 percent of those responding to the Times poll said Brown would "fight harder for Social Security." Twenty-one percent made that statement about Wilson.

Wilson campaign spokesman Otto Bos said the new poll reflected the "inordinate amount of money spent on television" by Brown.

Describing the Brown campaign as "unprecedented, not only in terms of money, but in terms of negativism," Bos said that Wilson would soon air television commercials that quote Los Angeles Mayor Tom Bradley, the Democratic gubernatorial nominee, as "criticizing Brown for letting the California highway system go to hell."

The Times poll was not totally good news for Brown, however. It showed that he still has high negative feelings among voters, with a 48 percent unfavorable rating among all voters, 71 percent among Republicans.

The poll also showed that Brown, who loses 23 percent of the Democratic vote to Wilson, has not been able to solidify support in his own party. More than half of the voters who expressed a preference for Wilson said it was due to a dislike of Brown rather than positive feelings toward Wilson.